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The Institute of Computer Graphics carries out research in a modern field that has been coined "visual computing". Our core disciplines cover the imaging, processing, visualization and displaying of visual data. These are enabled by new fields and technologies, such as light fields, projector-camera systems, responsive optics, mobile computing, and visual analytics.

Please select one of the following topics or years for detailed information.

Responsive Optics

Compressive Volumetric Light-Field Excitation

We explain how volumetric light-field excitation can be converted to a process that entirely avoids 3D reconstruction, deconvolution, and calibration of optical elements while taking scattering in the probe better into account. For spatially static probes, this is achieved by an efficient (one-time) light-transport sampling and light-field factorization. Individual probe particles (and arbitrary combinations thereof) can subsequently be excited in a dynamically controlled way while still supporting volumetric reconstruction of the entire probe in real-time based on a single light-field recording.

D. C. Schedl, O. Bimber, Compressive Volumetric Light-Field Excitation, Scientific Reports 7(13981), doi:10.1038/s41598-017-13136-2, 2017

application/pdfPaper (Preprint) (34.9 MB)

Volumetric Light-Field Excitation

Volumetric Light-Field Excitation

We explain how to concentrate light simultaneously at multiple selected volumetric positions by means of a 4D illumination light field.
First, to select target objects, a 4D imaging light field is captured.
A light field mask is then computed automatically for this selection to avoid illumination of the remaining areas.
With one-photon illumination, simultaneous generation of complex volumetric light patterns becomes possible.
As a full light-field can be captured and projected simultaneously at the desired exposure and excitation times, short readout and lighting durations are supported.

Schedl, D. C. and Bimber, O. Volumetric Light-Field Excitation. Nature Sci. Rep. 6, 29193; doi: 10.1038/srep29193, 2016

Link to Nature  (Neues Fenster)
application/pdfManuscript (24.2 MB)

Adaptive Coded Aperture Photography

We show how the intrinsically performed JPEG compression of many digital still cameras leaves margin for deriving and applying image-adapted coded apertures that support retention of the most important frequencies after compression. These coded apertures, together with subsequently applied image processing, enable a higher light throughput than corresponding circular apertures, while preserving adjusted focus, depth of field, and bokeh. Higher light throughput leads to proportionally higher signal-to-noise ratios and reduced compression noise, or -alternatively- to lower shutter times. We explain how adaptive coded apertures can be computed quickly, how they can be applied in lenses by using binary spatial light modulators, and how a resulting coded bokeh can be transformed into a common radial one.

Bimber, O., Qureshi, H., Grundhoefer, A., Grosse, M., and Danch, D., Adaptive Coded Aperture Photography, In proceedings of 7th International Symposium on Visual Computing (ISVC'11), 2011

Visual Computing Featuring Responsive Optics

The combination of advanced software algorithms and optics opens up new possibilities for display, imaging, and lighting. It makes possible responsive optical systems that adapt to particular situations automatically and dynamically. Visual computing is a relatively young research field that provides a foundation for many of these approaches. It represents a tight coupling between image synthesis, image analysis, and visual perception. While optics is all about image formation, visual computing deals with the general processing of images. This paper summarizes several examples that illustrate how graphics, vision, perception, and optics are combined to realize smart projectors, smart cameras, and smart light sources.

Bimber, O, Visual Computing Featuring Responsive Optics, invited paper, In proceedings of 27th Spring Conference on Computer Graphics (SCCG’11), 2011

application/pdfManuscript (9.5 MB)

Closed-Loop Feedback Illumination for Optical Inverse Tone-Mapping in Light Microscopy

We show that optical inverse tone-mapping (OITM) in light microscopy can improve the visibility of specimens, both when observed directly through the oculars and when imaged with a camera. In contrast to previous microscopy techniques, we pre-modulate the illumination based on the local modulation properties of the specimen itself. We explain how the modulation of uniform white light by a specimen can be estimated in real-time, even though the specimen is continuously but not uniformly illuminated. This information is processed and back-projected constantly, allowing the illumination to be adjusted on the fly if the specimen is moved or the focus or magnification of the microscope is changed. The contrast of the specimen's optical image can be enhanced, and high-intensity highlights can be suppressed. A formal pilot study with users indicates that this optimizes the visibility of spatial structures when observed through the oculars. We also demonstrate that the signal-to-noise (S/N) ratio in digital images of the specimen is higher if captured under an optimized rather than a uniform illumination. In contrast to advanced scanning techniques that maximize the S/N ratio using multiple measurements, our approach is fast because it requires only two images. This can be beneficial for image analysis in digital microscopy applications with real-time capturing demands.

Bimber, O., Klöck, D., Amano, T., Grundhöfer, A., and Kurz, D., Closed-Loop Feedback Illumination for Optical Inverse Tone-Mapping in Light Microscopy, IEEE Transactions on Visualization and Computer Graphics, 2010 (submitted: August 2009, accepted: July 2010)

application/pdfManuscript (37.6 MB)

Coded Aperture Projection

Coding a projector's aperture plane with adaptive patterns together with inverse filtering allow the depth-of-field of projected imagery to be increased. We present two prototypes and corresponding algorithms for static and programmable apertures. We also explain how these patterns can be computed at interactive rates, by taking into account the image content and limitations of the human visual system. Applications such as projector defocus compensation, high quality projector de-pixelation, and increased temporal contrast of projected video sequences can be supported. Coded apertures are a step towards next-generation auto-iris projector lenses.

Grosse, M., Wetzstein, G., Grundhöfer, A., and Bimber, O., Coded Aperture Projection, ACM Transactions on Graphics, 2010 (submitted: June 2009, accepted: March 2010)
ACM Siggraph 2010